The Hall-Heroult process for deriving aluminum from alumina is well known. Customarily, a cell or pot (hereinafter referred to as a "pot") includes a chamber that is filled with molten cryolite maintained at a temperature of about 1800.degree. F. Direct electrical current is passed through the cryolite from suspended carbon anodes to cathodes in the carbon lining of the cell or pot and into the collector bars or plates that are embedded in the bottom of the carbon lining. Energy from the electricity causes a crust to form over the top of the molten cryolite. Alumina is then added to the crust from supply bins above the cells and the electric current which passes through the crust drives off the oxygen atoms in the alumina leaving aluminum atoms in a molten state.
During the process, a chimney or other vent vents hot gasses formed during the process from the pot. The pot has an opening at the front end thereof which is used to siphon off molten aluminum periodically during the conducting of the process. This opening is devoid of any closure and when hot gasses are vented from the pot through the chimney, this action causes air from the room in which the pot is located to be sucked into the internal chamber of the pot. Such airflow reduces the temperature within the pot and requires the expenditure of energy to maintain the temperature of the pot at the desired temperature of about 1800.degree. F. If a closure could be provided to close this opening during conducting of the process but which closure could be easily removed to permit siphoning of molten aluminum from the cell chamber, the efficiency of the process could be enhanced. It is with this thought in mind that the present invention was developed.
The following prior art is known to Applicant:
U.S. Pat. No. 2,043,700 to Hamm PA1 U.S. Pat. No. 2,686,747 to Wurtz et al. PA1 U.S. Pat. No. 2,716,788 to Naramore PA1 U.S. Pat. No. 5,001,865 to Procton PA1 U.S. Pat. No. 5,470,445 to Murray et al. PA1 (1) In a first aspect, the inventive closure is intended to be used to cover an opening in an aluminum refining pot of the type used to conduct the Hall-Heroult process which is employed to derive aluminum from alumina. Such a device includes an opening employed to siphon molten aluminum off from a chamber of the pot. PA1 (2) The inventive closure is designed to be removably attachable over the opening of the pot to seal the opening and increase the efficiency of the pot. PA1 (3) The inventive closure is preferably made of a flexible fabric of a material that can withstand the high temperature, in the range of 1800.degree. F., within the chamber of the pot. The closure has a peripheral seal in the form of an enlarged bulbous bead that best facilitates sealing about the opening of the chamber. PA1 (4) In one preferred embodiment, at an upper portion of the closure, a hook-like appendage is formed facilitating hanging of the closure on an upstanding lip of the pot. Of course, other means of attachment may be suitably employed. PA1 (5) In a further aspect, in the preferred embodiment, a handle is provided on the closure allowing the user to grasp the closure and easily remove it from the opening to allow siphoning of molten aluminum from the chamber.
The present invention patentably distinguishes from the teachings of these patents, taken alone or in combination, as contemplating a removable closure for the opening in an aluminum refining pot that includes a flexible heat-resistant material having a peripheral sealing bead.